Color photographic film and process



Aug. 4, 1953 e. B. HARRISON ETAL 2,647,833

COLOR PHOTOGRAPHIC FILM AND PROCESS Filed Feb. 8, 1950 WHITE BLUE RED MAGENTA BLACK GREEN vsuaw cmN LJIIIIII] LAYER BLUE SENSITIVE LAYER.

YEILDW FILTER LAYER.

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RED SENSITIVE LAYER.

YELLOW FILTER LAYER.

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Mnanvm :0: 011A DEVEL aPk-"p mmaz, jcm/v (0100K DE VELOPED IMAfiE.

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Patented Aug. 4, 1953 UNITED STATES ATENT OFFICE COLOR PHOTOGRAPHIG FILM AND PROCESS Application February 8, 1950, Serial No. 143,157 In Great Britain February 9, 1949 13 Claims.

This invention relates to colour photography and particularly to methods and materials for obtaining corrected colour images.

Most of the modern processes of colour photography are based on the use of an integral tripack material which comprises a support and, superimposed on one side of the support, three silver halide emulsion layers, one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum, and the other is not specially sensitised. Silver halide emulsion layers are normally sensitive to blue, and accordingly it is arrauged that the notspecially-sensitised emulsion, which is sensitive to blue, is an outer layer of the three-emulsion layer assembly and there is provided a blue-absorbing filter layer between it and the remaining emulsion layers. Thus, when the material is exposed to a coloured object the blue, green and red records are recorded in their appropriate layers. Variations in the structure of the material are possible; for example the order of the layers may be varied.

For the sake of brevity the not-specially-sensitised emulsion will hereinafter be referred to as the blue-sensitive emulsion since it is in fact the only emulsion which is allowed to record the blue light received from the subject photographed. It will further be understood that in speaking of the blue-sensitive emulsion as an outer layer, it is meant that the blue-sensitive layer is not located between the other two layers; it may be closest to the support or the most remote from the support, but should in either case be the layer on which the light of the exposure is first incident.

The blue-absorbing filter layer referred to above may be of a character such that it persists through the processing of the tripa-ck and is only removed at the final stage of processing, or may be such that it is destroyed in the first development step applied to the tripack.

When a material of the type described above contains colour-formers," and is subjected to colour development, coloured images are formed in situ with the silver images. Colourformers are compounds which combine with the oxidation products formed during development by means of an aromatic primary amino developing agent, to form azomethine or quinoneimine dyestufi images in situ with the developed silver images, and colour development is the term applied to the production of such dyestufi images.

The colour-formers may be included in the emulsion layers or may be in layers adjacent thereto, or may be contained in colloid media, e. g. grains of hydrophilic colloid, dispersed through the emulsion layers.

By employing colour-formers which yield dyes which'are complementary to the sensitivity of the layers, i. e. a colour-former yielding a yellow dye in the blue-sensitive layer, a colour-former yielding a magenta dye in the green-sensitive layer, and a colour-former yielding a cyan dye in the red-sensitive layer, it is possible, by a reversal technique, to obtain a positive colour transparency in full colour.

In an alternative technique the original material may be processed to a negative and this may be copied on to another multilayer photographic material, which in turn may be developed to a positive: in this negative-positive technique the colour-formers present in the layers of the materials need not be such as will yield dyes complementary in colour to the sensitivities of the emulsions, but providing the dyes are respectively subtractive to the primaries they may be generated in any of the emulsion layers, the correction being effected by an appropriate choice of coloursensitivity and colour-former assembly in making the positive print. Such processes are referred to as false-colour processes and in further explanation of the technique, attention is drawn to British Patents Nos. 475,784 and 475,786.

Though processes such as those described above could theoretically yield excellent results, difiiculties arise in practice from several sources. A principal source of difficulty is that it is impossible to find three colour-formers which will yield ideally perfect dye images. There is always some departure from perfection and it is usually that the dye absorbs light of Wavelengths which it should, ideally, freely transmit. Cyan dyes generally absorb quite appreciably in the blue and green, while magenta dyes generally absorb too much in the blue. The net result is that the balance of the colours is disturbed and a true colour rendering is not obtained.

The present invention provides processes whereby the effect of the unwanted absorptions may be corrected, and it employs the technique now generally known as masking. In brief this technique amounts to the following: each dye image which absorbs light of wavelengths which it should ideally transmit is provided with a complementary image (1. e. a positive where the origirial is a negative and vice versa) which absorbs light of said wavelengths to an extent such that both images is substantially constant. It will be appreciated that by this means the effect of the unwanted absorptions is masked out in the sense that, over those wavelengths, the layer containing the dye image will cast no image on a printing material.

Many methods have been suggested for achieving this end. The bulk of them rely on the production of separate masks which are bound up in register with the original. Latterly, however, at-

tention has been directed to the production of masks which are formed integrally with the original material. The present invention is directed to an improved integral multipack which includes a layer destined to record a masking image and to the processing of such multipacks.

According to the present invention an integral multipack for colour photography which provides for the formation of an integral mask, comprises an assembly of three light-sensitive silver halide emulsion layers containing substantive colourformers (the image record layers) as in the normal form of tripack hereinbefore described, coated on a transparent support, there being provided in the position most remote from the bluesensitive image record layer a photographic silver halide emulsion layer (the masking layer) which is sensitive to the same colour as the image record layer which contains the substantive colour-former which gives rise to the dyestuff whose absorption is to be corrected, there also being provided between said masking layer and the said image record layers a blueabsorbing filter layer.

- One convenient form of multipack according to the invention comprises the following layers:

(a) A blue-sensitive silver bromide emulsion layer containing a substantive colour-former.

(b) A removable blue-absorbing filter layer.

A green-sensitive silver bromide emulsion layer containing a substantive colour-former.

(d) A red-sensitive silver bromide emulsion layer containing a substantive colour-former.

(e) A removable blue-absorbing filter layer.

(1) An emulsion layer sensitive to green or red or both.

(9) A transparent colourless support.

In the foregoing assembly the various layers are listed as being coated on one side of the transparent support (9) but this is not absolutely necessary, and modifications of the assembly, in which the order of the layers is varied, are possible. Thus, the three layers (e), (f) and (g) may be in the alternative order (e), (g), (f), or (g) (e) (f) Further, the order of the layers (0) and ((1) may be reversed. The removable blue absorbing layers (b) and (e) may consist of dischargeable dyestuifs or, in certain applications of the invention, may consist of colloidal silver. The colour-formers in the layers (a) (c) and (11) should, of course, be different from one another and should be selected from colour-formers yielding cyan, magenta and yellow dyes. The colourformer in layer (a) should yield a dyestuff which does not require correction or which it is not intended to correct. In practice this usually means that the colour-former in layer (a) should yield a yellow dye, while those in layers (0) and (d) yield magenta and cyan dyes. The emulsion layer (1) may be free of colour-former or may contain a colour-former for certain applications of the invention.

The following are examples of procedures which may be adopted for the production of image 4 records in layers (a), (c) and (d) together with a masking record in layer (1).

Procedure 1.(This procedure is illustrated in the accompanying drawing.) The element is exposed in a camera to light incident on layer (a) and is thereafter developed in a non-colour-forming developer, i. e. to produce negative silver records in layers (a), (0), (d) and (1) corresponding to the colour-sensitivity of those layers. The product is identified as Stage A in the drawing. Layer (f) is then exposed to blue light incident on the layer (9), or incident on the layer (1) if that forms the outside layer of the assembly. The blue-absorbing filter layer (e) serves to protect layers (a), (c) and (d) from this exposure. The element is then developed in a colour developer, e. g. N.N.-diethyl p-phenylene diamine, containing a colour-former which yields a dye image in a colour corresponding to the undesired absorption of the dyes derived from the colourformers in layers (0) or (d) or both. The element is then fixed in sodium thiosulphate and is shown as Stage B of the drawing. At this stage the element carries negative image records in silver in layers (a), (c) and (d) and a positive record in colour-formed dye in layer (1). The element is then subjected to treatment to convert the silver images to silver halide, for example by any normal bleaching treatment, and the bleached negative records are re-developed in a colour-forming developer such as N.N.-diethyl pphenylene diamine. Negative records in dyestuff are thus produced in layers (a), (c) and (d) together with silver images, and though silver may be re-developed in layer (1) no further dye image will be produced in this layer because it contains no colour-former. The silver and residual silver halide contained in the element are then removed by treatment in Farmers reducer so that the final product bears negative image records in layers (a), (c) and (d) and a positive masking record in layer (1). This is shown as Stage 0 of the drawing.

Procedure .2.The element as defined above is exposed by means of light incident on layer (a) and is developed in a colour developer such as N.N.-diethyl p-phenylene diamine. This development may be brought to completion by a subsequent treatment in a vigorous non-colour-forming developer. There are thus obtained negative image records in silver and dye in each of layers (a), (c) and (d) and a negative silver record only in layer (f). Layer (f) is then re-exposed to blue light incident on layer (g) or on layer (j) if that forms an outside layer of the assembly. Residual silver halide in layers (a), (c) and (d) is protected by the blue-absorbing filter layer (e). The element is then developed in a colour developer containing a colour-former yielding a dye corresponding to the undesired absorption of the dyes produced in layers (0) or (d) or both. The silver images and residual silver halide are then removed by treatment in Farmers reducer leav ing a product in which there are negative image records in dyestuffs in layers (a), (c) and (d) and a positive image record in dyestufi in layer (f).

Procedure 3.--This procedure may be adopted if it is desired that the masking image should be a silver image rather than an image in dyestufl. The photographic element is exposed to light incident on layer (a) and is then developed in a colour developer. This produces negative image records in layers (a), (c) and (d) made up of dyestufi' and silver, and a negative image record in layer (f) consisting only of silver. This development ride.

step; may bebrought to completion. if; desired by a subsequent treatment, ina-v vigorous; black and white; developer. The element is. then.- treated with a bath containing cupricchloride which-has the: effect: of converting the silverto. silver chlo- This-is followed by treatment in a bath of sodium sulphite which has the: property of dis solving out. the. silver chloride while leaving the silver-bromideoftheoriginalemulsionlayerssubstantially unafiected. The. element is thenex.- posed to blue light incident. on layer; (a), cronlayer (7) if; that forms an. outer layer of the assembly, and is developed inanormal'non-colourformingdeveloper. In this way there is produced apositivesilver record inlayer- (I). The element is a then fixed in sodium thiosulphate, thus removing all-theresidual silver-bromide and silverxchloride, Theproduct thus obtained contains negative record images-in dyestufiin-layers (a), (c); and. (d-)- and a positive maskingimage in silver in layer (f).

Procedure 4.-This;procedure may be adopted to obtain a colour. record by the reversal pro.- cedure. The element must-be one-in which the filter layer (b) is formed by a dyestufi which is readily removable-asa preliminary operation, say; most conveniently, in the first development step. Further,. the filter layer (e) must be formed of dyestuft which is relatively stable and will resist the. usual developing, fixing and bleaching treatments. A. 'dyestuifi suitable for layer (b) is Tartrazine.whichwashes out in alkaline developer, and a dyestufl suitable for layer (e)- is a complexq of Auramine base and hexadecyl sodium sulphate; The following. procedure is then adopted The element is exposed in a camera. to light incident on layer (a) and'is thereafter developed in a non-colour-forming developer; This-yields negative-silver records in layers (a), (c), (d) and (fr) corresponding, to the colour-sensitivity of' those layers; and it. also decolourises" layer (12).. Layers (a), (c) and (d) are then re-exposed by means of: blue light incident on layer (a), the layer (e): serving: to. prevent re-exposure of layer; (f); The element. is then developed in a. colour developer, e. ghNiNg-diethyl p-phenylene diamine, and fixed in sodium. thiosulphate. At this stage thereare negative silver record images; in layers (at), (d y and (f) and positive record images in-.silver and dyestufi: in layers (a) (c) and- (d) The element-is then treated ina bathwhich, con-- vertsallthesilver to an insoluble silver salt which islight-sensitive; for example: a bath containingpotassium; ferricyanide and. potassium bromide. The element: is then: re-exposed with" blue light; incident on: layer (f), the filter layer- (a). serving to;- prevent re-exposure of therecord layers: (it), (c) and (d). The element is then developed in one-of three ways (i) in a non-colour-forming' developer which produces anegative silver image. in layer (f) (ii) in a colour developer-containing a colour-former which produces a negative imagein silverand dyestufi: in. layer (f) (iii) (if the layer contains. a substantive colour-former) in. a colour developer: not containing a colourformer. The element is then treated to fix out the silver salts; andzif. method (ii) on(iii) is used the; layer is: treated to: bleach. the negative-silver record in layer- (f) prior" to the fixing; operation. Finally, the filter material: isaremoved from layer (e).-,. for example by treating that layer with dodecyla pyridinium. bromide, and: washing: The:

final. product contains pcsitivedye image records in layers (a) ,l (-c): and. (d),- and: a negative masklit) ingrecordin silver ordyestuffqor bothin layer (f-L.

Whatwe claim is:

1., Any integral multipack forcolour photogra phy which.comprisesianzassembly of. three lights sensitive; image-recording silver halide emulsion layers-selectively sensitised to blue, green and red light; and: each containing a substantive. colourformer which couples with the: oxidation product of i an aromatic primary aminodeveloping agent to; yield a dye,- the said colour-formers yielding; dyes: which are subtractive primary colours. the: saidlayers; being coated on a transparent sup.- port: with the red and green-sensitive layers adijacent. and the blue sensitive layer on one sideof them, aphotographic silver halidemasking layer located in the position most remote from thexbluea sensitive image-recording layer; saidmasking layer being sensitive to light of the same waveband as one of the image-recording layers which contains a. colour-former giving rise, by colourdevelopment, to a dyestuii which absorbs. un-e desirably in a waveband which it should desirably transmit, and a: blue-absorbing filter layer, the colour of which is resistant to development; -lo;--

cated between the said masking layer and the.

said" image-recording: layers.

2. An integral multipack. for colour photographywhich comprises; the; following layers in superposition: (a) a blue-sensitive silver bromide emulsion layer containing a substantive colourformer which couples with the oxidation product of an. aromatic primary: amino. developing agent; (b) a removableblue-absorbing filter layer, (0) a green-sensitive silver bromide emulsion layer containing a substantive. colour-former which couples with the oxidation product of an aromatic primary amino; developing agent, (d)1 a redsensitive silver-bromide emulsion layer containing a substantive colour-former which couples with the. oxidation. product: of an aromatic primaryamino developing: agent; (e) a removable blueabsorbing: filter layer,.the.-colour of which is. re-'' sistant todevelopment, (f) a silver bromide emu-l sion layer sensitive to atv least one of green and red; (99 a. transparent. colourless support; the. said: colour-formers. yielding dyes which are the three subtractive primary: colours.

3'; An: integral. nrultipack for colour photography which comprises: the following layers insuperposition:- (a) a blue-sensitive silver: bro-- mide emulsion layer containing: a substantive colour-former which couples with the oxidation.

product of an aromatic primary amino developing, agent, (12). a removableblue-absorbing filter layer, (0) a green-sensitive silver bromide emulsion layer containing: a. substantive colour-former whichcouples. withthe. oxidation product of an aromatic primary amino. developing, agent, (d) a red-sensitive silver bromide emulsion. layer containing a substantive colour-former which. coue pics with the oxidation product. of an aromatic primary amino developing agent, (e) a remov ableblue-absorbing filter layer, the. colour of" which is resistant to development, (I) a trans parent colourless support, (g) a silver bromide I emulsion layer sensitive to at least one of green and red; the said colour-formers yielding dyes which arethe three subtractive primary colours;

4-. An integral multipack for colour photography which comprises the following layers in uct: of an aromatic; primary amino developing agent, (-b) a removable blue-absorbing filter layer, a green-sensitive silver bromide emulsion layer containing a substantive colourformer which couples with the oxidation product'of an aromatic primary amino developing agent, (d) a red-sensitive silver bromide emulsion layer containing a substantive colour-former which couples with the oxidation product of an aromatic primary amino developing agent, (6) a transparent colourless support, (1) a removable blue-absorbing filter layer, the colour of which is resistant to development, (9) a silver bromide emulsion layer sensitive to at least one of green and red; the said colour-formers yielding dyes which are the three subtractive primary colours.

5. An integral multipack for colour photography which comprises the following layers in superposition: (a) a blue-sensitive silver bromide emulsion layer containing a substantive colour-former which couples with the oxidation product of an aromatic primary amino developing agent, (b) a removable blue-absorbing filter layer, (0) a red-sensitive silver bromide emulsion layer containing a substantive colour-former which couples with the oxidation product of an aromatic primary amino developing agent, (01) a green-sensitive silver bromide emulsion layer containing a substantive colour-former which couples with the oxidation product of an aromatic primary amino developing agent, (e) a removable blue-absorbin filter layer, the colour of which is resistant to development, (I) a silver bromide emulsion layer sensitive to at least one of green and red, (9) a transparent colourless support; the said colour-formers yielding dyes which are the three subtractive primary colours.

6. An integral multipack for colour photography which comprises the following layers in superposition: (a) a blue-sensitive silver bromide emulsion layer containing a substantive yellow colour-former which couples with the oxidation product of an aromatic primary amino developing agent, (b) a removable blue-absorbing filter layer, (0) a green-sensitive silver bromide emulsion layer containing a substantive magenta colour-former which couples with the oxidation product of an aromatic primary amino developin agent, (d) a red-sensitive silver bromide emulsion layer containing a substantive cyan colour-former which couples with the oxidation product of an aromatic primary amino developing agent, (6) a removable blue-absorbing filter layer, the colour of which is resistant to development, (1) a silver bromide emulsion layer sensitive to at least one of green and red, (g) a transparent colourless support.

7. An integral multipack for colour photography which comprises the following layers in superposition: (a) a blue-sensitive silver bromide emulsion layer containing a substantive yellow colour-former which couples with the oxidation product of an aromatic primary amino developing agent, (b) a removable blue-absorbing filter layer, (0) a red-sensitive silver bromide emulsion layer containing a substantive cyan colourformer which couples with the oxidation product of an aromatic primary amino developing agent, (d) a green-sensitive silver bromide emulsion layier containing a substantive magenta colour-former which couples with the oxidation product of an aromatic primary amino developing agent, (e) a removable blue-absorbing filter layer, the colour of which is resistant to development, (f) a silver bromide emulsion layer sensitive to at least one of green and red, (9) a trans parent colourless support.

8. Process for the production of a masked colour photographic record which comprises exposing an element according to claim 2 to light incident on layer (a), developing in a noncolour-forming developer, exposing layer (,f) to blue light incident on layer (9), developing in a primary aromatic amino developing agent which contains a colour-former which yields a dye in a colour corresponding to the undesired absorption of the dye derived from the colour-former in at least one of the layers (0) and (d), fixing, bleaching the silver images to silver halide, redeveloping the images in a primary aromatic amino developing agent and thereafter removing silver and silver salts from the product, and at any stage after the second exposure operation removing the colour from the layer (e).

9. Process for the production of a masked colour photographic record which comprises exposing an element according to claim 2 to light incident on layer (a), developing in a colourforming developer, re-exposing layer (1) to blue light incident on layer (9), developing in a primary aromatic amino developing agent which contains a colour-former yielding a dye corre* sponding to the undesired absorption of at least one of the dyes formed in layers (0) and (d), and thereafter removing silver and silver salts from the product, and at any stage after the second exposure operation removing the colour from the layer (e).

10. Process for the production of a masked colour photographic record which comprises exposing an element according to claim 2 to light incident on layer (a), developing in a primary aromatic amino developing agent, bleaching the silver images to silver chloride and dissolving out the silver chloride thus formed While leaving the silver bromide of the original emulsion unaffected, re-exposing the element to blue light incident on layer (g), developing in a non-colour-forming developer and fixing the product, and at any stage after the second exposure operation removing the colour from the layer (e).

11. Process for the production of a masked colour photographic record which comprises exposing an element according to claim 2, in which layer (1)) comprises a readily removable dyestuff and layer (e) comprises a dyestuff which is resistant to normal processing, to light incident on layer (a), developing in a non-colourforming developer and simultaneously decolourising layer (b), re-exposing the element to blue light incident on layer (a), developing in a primary aromatic amino developing agent, fixing, bleaching the silver images to a light-sensitive silver salt, re-exposing with blue light incident on layer (1), developing in a non-colour-forming developer, fixing and removing the dyestufi" from layer (e).

12. Process for the production of a masked colour photographic record which comprises exposing an element according to claim 2, in which layer (17) comprises a readily removable dyestuff and layer (e) comprises a dyestuif which is'resistant to normal processing, to light incident on layer (a), developing in a non-colourforming developer and simultaneously decolourising layer (2)), re-exposing the element to blue light incident on layer (a), developing in a primary aromatic amino developing agent, fixing, bleaching the silver images to a light-sensitive silver salt, re-exposing with blue light incident on layer (f5, developing in a primary aromatic amino developing agent which contains a colourformer Which combines with the oxidation products of said developing agent, bleaching the silver image thus formed to silver salt, fixing out all silver salts contained in the element and removing the dyestuff from layer (e).

13. Process for the production of a masked color photographic record which comprises exposing an element according to claim 2, in which layer (f) contains a substantive colour-former which couples with the oxidation product of an aromatic primary amino developing agent, layer (2)) comprises a readily removable dyestuif and 'layer (e) comprises a dyestufi which is resistant 'to normal processing, to light incident on layer (a), developing in a non-colour-forming developer and simultaneously decolourising layer -(b), re-exposing the element to blue light incident on layer (a), developing in a primary aro- Jmatic amino developing agent, fixing, bleaching the silver images to a light-sensitive silver salt,

-i e-exposing with blue light incident on layer References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,153,617 Eggert et al. Apr. 11, 1939 2,258,187 Marines et al. Oct. '7, 1941 2,316,803 Michaelis Apr. 20, 1943 2,348,735 Gaspar May 16, 1944 2,393,756 Dearing Jan. 29, 1946 2,192,954 Ball et a1. Jan. 3, 1950 FOREIGN PATENTS Number Country Date 828,754 France Feb. 28, 1938 483,035 Great Britain Apr. 11, 1938 

1. AN INTEGRAL MULTIPACK FOR COLOUR PHOTOGRAPHY WHICH COMPRISES AN ASSEMBLY OF THREE LIGHTSENSITIVE IMAGE-RECORDING SILVER HALIDE EMULSION LAYER SELECTIVELY SENSITISED TO BLUE, GREEN AND RED LIGHT AND EACH CONTAINING A SUBSTANTIVE COLOURFORMER WHICH COUPLES WITH THE OXIDATION PRODUCT OF AN AROMATIC PRIMARY AMINO DEVELOPING AGENT TO YIELD A DYE, THE SAID COLOUR-FORMERS YIELDING DYES WHICH ARE SUBTRACTIVE PRIMARY COLOURS, THE SAID LAYERS BEING COATED ON A TRANSPARENT SUPPORT WITH THE RED AND GREEN-SENSITIVE LAYERS ADJACENT AND THE BLUE-SENSITIVE LAYER ON ONE SIDE OF THEM, A PHOTOGRAPHIC SILVER HALIDE MASKING LAYER LOCATED IN THE POSITION MOST REMOTE FROM THE BLUESENSITIVE IMAGE-RECORDING LAYER, SAID MASKING LAYER BEING SENSITIVE TO LIGHT OF THE SAME WAVEBAND AS ONE OF THE IMAGE-RECORDING LAYERS WHICH CONTAINS A COLOUR-FORMER GIVING RISE, BY COLOUR DEVELOPMENT, TO A DYESTUFF WHICH ABSORBS UNDESIRABLY IN A WAVEBAND WHICH IT SHOULD DESIRABLY TRANSMIT, AND A BLUE-ABSORBING FILTER LAYER, THE COLOUR OF WHICH IS RESISTANT TO DEVELOPMENT, LOCATED BETWEEN THE SAID MASKING LAYER AND THE SAID IMAGE-RECORDING LAYERS. 